Peeves and Dumbles: It's more likely that Peeves respects the position, not the person; and Dumbles probalbly hinted that he'd have him exorcised. Perhaps the other ghosts could add a little misery to Dumbles year..... (whistles innocently) If they've been whammied like McGonagall and can now break free I'm sure that they'd have a few ideas to add! Peeves might have been saving up retribution for a very long time...... I meant that the elves could help the students with their meditation; for example teaching them them how to create their crystals. It would also give them first hand proof of the elves' skills at things besides cleaning and cooking. Sometimes the support troops get forgotten but the ones who they're helping. Dobby might be the only one who can use a saber, but the others could be the equivalent of the Jedi Agricorp or medical units in some of the stuff I've read. As always, thanks for another excellent chapter!
Canon is one thing, but I can see the sneaky underhanded bastard I've created, doing just that. I'm not certain about the other ghosts. While Peeves seems to be less vulnerable to removal, exorcising any of the other ghosts, might send them...elsewhere. Sir Nicholas told Harry that the reason he was a ghost was that he was afraid to cross over, but hinted that it was a one-time choice. What if it is? What if when the ghosts decide to stay, they lose the option and if they're exorcised, would they just vanish, as if they never were? That would be a pretty horrible thing for a ghost.
The castle ghosts seem rather stogy to me, though It's possible. The castle elves are all bound to Hoggys, and so would probably have a heart attack even considering the idea of pranking Dumbley. Sigh!
That's where the 'terrible trio' come in. Peeves is mischievous and often malicious, but he's not vindictive. He lives for the moment.
I see your point about the elves. And it's a good idea. I hadn't considered that specific point, they would be the best to help create the perfect stones Harry insists on, but I have some time before the training begins. Dobby will certainly be training with the first group, but later he will be helping to train the rest. Perhaps the other force sensitive elves will act as teachers, guiding the students in various arts.
In teaching the students how to make their own crystals... That will happen. I intend for the 'final exam' as it were to be building their own lightsaber including creating their own focusing crystal, preferably the diamond encased type that Harry, Hermione and Dobby carry,(Hermione will be creating one of her own.) one of the force sensitive elves will pair off with each student who is ready, and help him or her to create the stone. They also have orders to not treat any of the students as 'extra special'.
The elves, along with a few humans, will be the supply/logistics group that keep his fighting team running, and truly Harry wouldn't be able to do the job without them. He's also got a surprise in store for the last part, where the elves will be indispensable.